Knife-wielding thugs threatened staff during two raids on Co-op stores in Sheffield.
Police say three masked men entered the Co-op on Greengate Lane in High Green and threatened staff members to open the till and safe.
The incident occurred at around 7.20pm on Sunday and the group fled with a quantity of cash.
Officer say the men had their heads and faces covered and were wearing dark jackets and trousers.
A second Co-op store was targeted two hours later where two men armed with a knife entered the store on Burncross Road in Chapeltown.
The men, who had their faces covered, forced a staff member to open the safe. A quantity of cash and tobacco was taken.
No-one was injured in any of the raids and officers are trying to ascertain if the incidents are linked in any way.
Detective Sergeant Cath Abou-Ragheb from South Yorkshire Police is leading the investigation.
She said: “These were two very distressing incidents, in neighbouring villages within a short space of time of each other.
“While no-one was injured, the staff understandably were incredibly shaken up and are being supported by officers.
“I can reassure people living in these communities that a full investigation is underway and that we are working to establish whether the incidents are linked.
“We are keen to hear from anyone who was in either area around the time of the offences – did you hear or see anything suspicious? If so, please do get in touch.”
To report information about the High Green robbery please contact 101 quoting incident 947 of 18 March 2018.
To report information about the Chapeltown robbery please quote incident 1077 of 18 March 2018.